Saturday, November 06, 2010

Harris Hawk X Golden Eagle

Harris Hawk X Golden Eagle in midflight.  Click to enlarge.

As I noted a while back in a post about species loss, a good case can be made that more species are provably being created every year than being driven to extinction. To be clear, I am not saying that species extinction is not a very, very serious problem, only that we should at least mention that useful species and subspecies are being created every day, and in every key type:  fur, fin and feather.   In the history of the world, I am pretty sure the creation of the leghorn chicken is more important than the loss of a subspecies of finch found only on one isolated atoll in the Pacific.

Several examples of speciation (it is a process, not an event) can be found in the world of falconry, where advances in aviary management and artificial insemination have resulted in all kinds of hybrids, such as Gyr/Peregrine and Gyr/Saker crosses that are not only fertile, but which combine the useful characteristics of one species (such as the speed of the Peregrine) with the useful characteristics of another (such as the size and strength of the Gyrfalcon).

The first hybrid falcons were produced in 1971 in western Ireland when falconers Ronald Stevens and John Morris put a male Saker into a moulting mew with a female peregrine. The two young falconers were quite astonished when the birds mated and produced viable hybrid chicks.

Soon other hybrids were being produced, revealing both the extreme plasticity and suspect nature of raptor classification.

One factor driving advances in falcon and hawk hybridization is that in Britain it is now illegal to use wild-caught birds of any kind for falconry. As a consequence, British hawkers and falconers are entirely dependent on captive-bred birds and are eager to fly birds that are demonstrably not wild-born, hence an affinity for hybrids.

Perhaps the most unusual hybrid created in recent years is a cross between a Harris Hawk and a Golden Eagle. These birds have only recently been created by S.&S. Falconry in Canada, and it remains to be seen whether the docile and biddable brain of a Harris Hawk can be reliably placed within the larger body of a Golden Eagle. If so, we will surely end up with the ultimate Jack Rabbit-hunting raptor, as the pictures above, and below, suggest.

Success with a Harris Hawk-Golden Eagle hybrid.

What makes this mating so unusual, of course, is that we have not only crossed the species line, but we have crossed the genera and subfamily line as well. 

An eagle crossing with a hawk?  Impossible!   But of course, apparently, it's not.   A Buteoninae (hawk) of the genus Parabuteo and the species unicinctus will produce viable young when crossed with a Aquilinae (eagle) of the genus Aquila and the species chrysaetos.   The mind riots.

And, of course, that's not the only "out-of-bounds" cross that's possible.    Cooper’s hawk (Accipiter cooperii) and Red-tailed hawks (Buteo jamaicensis) will also cross with Harris’s hawks (Parabuteo unicinctus).

None of this is likely to have too much effect on the wild, by the way, other than to make sure that most wild-caught birds are left alone to breed freely. 

Today, most falconers and hawkers, the world over, are using captive-bred birds, and many of the female hybrid crosses lay infertile eggs.  But not all of them.  And, of course, the male birds are generally very fertile. 

So, yes, some introduction of genetic variability into the great web of life is possible, but that has always been true, and it is always happening (at a very low level) in the wild.  A Grizzly bear can mate with a Polar bear and have fertile young, and yes that occasionally happens in northern Canada and Alaska.   Natural Saker and Gyrfalcon crosses are fairly common, and quite fertile, while certain ducks and fish species hybridize all the time.  Cougar and Jaguar hybrids occasionally occur in the wild, along with Lynx and Bobcat hybrids

Most naturally occurring hybrids go nowhere, of course, some because they are infertile, others because they send the wrong mating signals.   In extreme cases, such as crosses between Mule Deer and Whitetail, the result is otherwise maladaptive.  When startled,  mule-whitetail crosses do not know if they are to bounce away like a mule, or run like a whitetail.  The result:  they tend to get so confused they are quickly eaten!

But of course, stable hybrids are found in the wild, no matter how distressing that idea is to armchair theorists.  For example, DNA research has proven what has always been suspected -- that the Eastern Red Wolf in the U.S. is nothing more than a stable hybrid of a Grey Wolf and a Coyote.

Special thanks to Teddy M. for sending the pics and telling me of this unusual raptor cross!  Not sure who the pics are from, but hat's off for the terrific shots and let me know if you don't want them used.


Doug said...

Great article Patrick. I hope you don't mind if I cross post.

PBurns said...

Mind? No, thrilled!



grapfhics said...

Interesting post, and one that should remind everyone that evolution does not limit reproduction to within the same species. Some survive and others die out. It's a tough battle, survival of the fittest is not for wimps nor
lab rats.

Isaac said...

There was a bird recently banded by a long time bander/falconer that appears to be a natural goshawk/Cooper's hawk cross. It's causing a bit of debate on one of the falconry forums. I'll email some photo's in a bit. Beautiful bird!